Abstract
Methods of extracting the monosubstituted (Sakaguchi-positive) guanidines of brain, and of their chromatographic characterization, are described. The occurrence of free arginine, glycocyamine and gamma-guanidobutyric acid is confirmed, and evidence for the presence of taurocyamine is presented. Concentrations of these compounds are approximately 0.03-0.1 [mu]mole/g of tissue, which corresponds to about 1% of the free creatine of the brain.